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G. A. RANDALL. Telephonic Receiving Apparatus.

No. 237,046. v Patented .Ian. 25, I881.

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MPETEHS. PHOTO-LITHOGRAFHEH, \vAsHmGTON, D C.

UNITED STATES PATENT OFFICE.

CHARLES A. RANDALL, OF NEW YORK, N. Y.

TELEPHONIC RECEIVING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 237,046, dated January 25, 1881.

Application filed November 3, 1880.

To all whom it may concern:

Be it known that I, CHARLES A. RANDALL, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented new and useful Improvements in Telephonic Receiving Apparatus, of which the following is a specification.

This invention relates to a telephonic receiving apparatus operated bya local battery, and especially designed for use in connection with a transmitting apparatus arranged to make and break circuit over a main line or to send reverse currents over the line in response to the vibrations of a transmitting-diaphragm or equivalent vibrator. Its objects are to amplify and qualify the effect of the main-line current or currents and communicate to the receiverdiaphragm vibrations exceeding in force and amplitude such as could be produced by said main-line current or currents directly, and to simplify telephonic station apparatus by combining a signal or call with the receiver in such manner as to be operated in response to the vibrations of the transmitter-(1iaphragm.

It consists, mainly, in the combination, in a telephonic receiving apparatus, of an electromagnet arranged for connection with a main line, a tension-changer operated by said magnet and arranged to control a local circuit including a receiver, and a bell-ringing apparatus arranged for operation by said magnet, whereby a double function is given to said magnet and the telephone-station apparatus simplified.

It consists, further, in a novel construction and arrangement of a telephonic station apparatus, as will be hereinafter fully described.

The accompanying drawing is a side elevation, partly in section, of myimproved receivin g apparatus.

The letters A and A designate electro-magnets, in this instance composed of single helices and straight cores. These magnets are embraced by bands or casings B and B, supported by pedestals I) and b, resting upon a base, D, and provided with eyes 0, loosely embracing horizontal screws 0 and C, projecting from short standards d d, secured to the base. 011 opposite sides of the eyes 0 nuts 0 are arranged upon the screws 0 and G, for adjusting and securing the pedestals and magnets in position.

(No model.)

One terminal of the helix of magnet Ais connected to the line-wire L, and the other to p a wire, 1, leading to the ground, and said mag net is provided at its inner end with armature F, secured to metallic plate-spring g, the lower end of which is secured to metal lug h, fixed to the base, and the upper end to an arm projecting from a post, From the back of the armatureFa platinum stud,f, projects through an aperture in the spring g, and has its tip in contact witha carbon block, K, surrounded and closely held bya metal band, k, carried by aleafspring, m, the lower end of which is secured to a lug, n, fixed to the base, said leaf-spring being preferably formed of hard rubber, ivory, or some other elastic non-metallic substance, in order to avoid the peculiar action of metal springs, which set up an independent vibration which is communicated to the receiver and interferes with its articulation.

The helix of the magnet A has one of its terminals connected with the carbon K by a wire, 0, the other terminal being connected, by a wire, 19, with one pole of a local battery, Q, the opposite pole of which is connected with the spring 1 by a wire, q.

The letter It indicates a diaphragm-in this instance supposed to be metallicsupported in front of the outer pole of magnet A by having its margin clamped between two rings, 8 s, of wood or other non-conducting material. (Shown in section.) To the ring 8 is secured an ear piece, S, as usual in receiving-telephones, and to this ear-piece is secured a box, T, around an opening in the wall of which the mouth of the ear-piece is fitted. One side of the box T is left entirely open, preferably at the right or left, and not in front, of the earpiece, the front wall of box being left to receive directly the vibrations of the air caused by the diaphragm. The office of the box T is simply that of an ordinary resonator for increasing the loudness and volume of the sounds produced by the diaphragm, and obviating the necessity of the close application of the ear of the listener to the ear-piece.

A lever, U, pivoted at its lower end to suitable lugs on the base, is provided with an armature, u, arranged within the field of attraction of the outer pole of magnet A, and said lever has its upper end extended to carry a bell-hammer for striking the bellY, mounted on a post projecting from the base. The backward movement of the lever U is limited by an adjustable screw, w, arrangedin a post, W', and said lever is retracted by a spring, w, the tension of which is regulated by a screw, to, arranged in said post.

The operation of the receiving apparatus, as now described, is as follows When rapidlyintermittent currents or impulses are sent over the line-wire by means of a transmitter, the core of magnet A is alternately magnetized and demagnetized, attracting and releasing the armature F, and thus causing the pressure of the platinum stud f upon the carbon block K to be alternately diminished or increased, and this diminution and increase of pressurecontact between the platinum stud and carbon block varies the flow of the current of the local battery Q over wire q, spring g, stud f, carbon block K, wire 0, helix of magnet A, and wire 19, thus varying the power with which said magnet A attracts the diaphragm R, and causing said diaphragm to produce sounds corresponding to those which set the diaphragm of the transmitter in motion, but much louder than could be produced by the vibrations of a diaphragm actuated directly by magnet A under the influence of the line current, because the great resistance oft the main line weakens the current to such an extent that its influence is very feeble. It is, however, strong enough to vary the contact pressure between the stud fand carbon K, and thus vary the tension of the current of the local battery, which traversing only a short circuit, exerts almost its entire electromotive forcein varying the power of magnet A. The sound-vibrations of the diaphragm R are communicated by the air to the box or resonator T, the vibrations of which produce sounds of greatly-increased volume, which may be readily heard in the vicinity without the necessity gt applying the ear to theear-piece, as heretoore.

The rapid intermittent currents of conversational communication do not affect the armature a of the. bell-hammer lever, the tension of the spring to being so regulated that said armature will be attracted only when specially slow impulses are sent over theline by means of loud sounds at the transmitter.

On circuits of moderate length the bell may be dispensed with, and intermittent currents of equal duration will cause a loud buzzing sound at the receiver. The bell, however, is preferable, as with it definite numbers of taps for signals may be struck.

I do not confine myself to the precise construction of apparatus shown in the drawing, as this may be greatly varied without departing from the principle of my invention. For instance, the ear-piece S and ring 8 may be dispensed with, and the edges of the wall of the resonator may be used, instead of ring 8, to clamp the diaphragm to ring .9.

Also, the magnets A A may be of ordinary construction, having two helices. The armature F and its supporting-spring may be replaced by a diaphragm, and the metallic diaphragm B may be replaced by a non-metallic diaphragm carrying a metallic armature.

The carbon block K may be fixed instead of yielding, or may be so arranged that in its vibrations it will come in contact alternately with opposite electrodes of the local battery and cause reversed currents to vitalize the magnet A.

The magnet A, instead of acting directly upon the diaphragm or armature of the receiver, may be used to operate a second tension-changer in a local circuit with a third magnet. Said third magnet, thus being energized to an extra power, may cause greatly-in creased vibrations in a receiver-diaphragm.

What I claim is-- 1. In a telephonic receiving apparatus, the combination of an electro-magnet arranged for connection with a main line, a tensionchanger operated by said magnet, and arranged to control a local circuit including a receiver and a bell-ringing apparatus arranged for operation by said magnet, substantially as described.

2. The combination of the magnet A, arranged for connection with a main line, the magnet A, included in a local circuit, a tension-changer arranged for operation by magnet A for varying the tension of said local circuit, and a receiver-diaphra gm arranged for operation by said magnet A, the said magnets, tension-changer, and diaphragm being mounted upon a single base, substantially as described.

3. The combination of the adjustable magnet A, arranged for connection with a main line, the armature F, provided with a stud, f, the carbon block K, the adjustable magnet A, having one terminal of its helix connected with saidblock and the other with one pole of a local battery, the opposite pole of which is connected with the armature F of the magnet A, and a receiver-diaphragm arranged for operation by said magnet A, substantially as described.

4. A magnet supported upon a pedestal provided with an opening or eye, in combination with a suitable supported screw extending through said opening or eye, and adjustingnuts arranged upon said screw for adjusting and securing said pedestal and magnet in position, substantially as described.

5. A carbon contact-piece carried by an elastic non-metallic support, in combination with a movable pressure device arranged to act upon said carbon for controlling the flow of an electric current therethrough, substantially as and for the purpose set forth.

In testimony whereof I have hereunto set my hand and seal in the presence of two subscribing witnesses.

o. A. RANDALL. .t. s.]

Witnesses:

CHAS. W. W. BALL, GEo. M. BAKER. 

